Biophotonics is the biomedical field relating to the electronic control of photons, i.e. light, and its interaction with living cells and tissue. Biophotonics includes surgery, imaging, biometrics, disease detection, and phototherapy. Phototherapy is the controlled application of light photons, typically infrared, visible and ultraviolet light, for medically therapeutic purposes including combating injury, disease, and immune system distress.
FIG. 1 illustrates elements of a phototherapy system including an LED driver 1 controlling and driving LEDs as a source of photons 3 emanated from LED pad 2 on tissue 4 for a patient 5. Although the patient 5 is represented by a human brain, any organ or tissue may be treated using phototherapy. Before and after, or during treatment, a doctor or clinician 7 may adjust the treatment by controlling the settings of LED driver 1 in accordance with observations from a monitor 6.
While there are many potential mechanisms, as shown in FIG. 2, the dominant photobiological process 22 responsible for phototherapy occurs within mitochondria 21, an organelle present in every eukaryotic cell 20 comprising both plants and animals including mammals, horses, and humans. To the present understanding, photobiological process 22 involves photon 23 impinging, among others, molecule cytochrome-c oxidase 24, represented symbolically as CCO, which acts as a battery charger increasing the cellular energy content by transforming adenosine monophosphate (AMP) into a higher energy molecule adenosine diphosphate (ADP), and converting ADP into an even higher energy molecule adenosine triphosphate (ATP), in the process of increasing, stored energy in the AMP to ADP to ATP charging sequence 25, cytochrome-c oxidase 24 acts in the manner of a battery charger, with ATP 26 acting as a cellular battery storing energy, a process which could be considered animal “photosynthesis”. Cytochrome-c oxidase 24 is also capable of converting energy from glucose resulting from digestion of food to fuel the in the ATP charging, sequence 25, or through a combination of digestion and photosynthesis.
To power cellular metabolism, ATP 26 is able to release energy 29 through a ATP to ADP to AMP discharging process 28. Energy 29 is then used to drive protein synthesis including the formation of catalysts, enzymes, DNA polymerase, and other biomolecules.
Another aspect of photobiological process 22 is that cytochrome-c oxidase 24 is a scavenger for NO 27, i.e. nitric oxide, an important signaling molecule in neuron communication and angiogenesis, the growth of new arteries and capillaries. Illumination of cytochrome-c oxidase 24 in cells treated during phototherapy releases NO 27 in the vicinity of injured or infected tissue, increasing blood flow and oxygen delivery to the treated tissue, accelerating healing, tissue repair, and immune response.
To perform phototherapy and stimulate cytochrome-c oxidase 24 to absorb energy from a photon 23, the intervening tissue between the light source and the tissue absorbing light cannot block or absorb the light. The electromagnetic radiation (EMR) molecular absorption spectrum of human tissue is illustrated in a graph 40 of absorption coefficient versus the wavelength of electromagnetic radiation λ (measured in nm) as shown in FIG. 3. As illustrated, the absorption spectra of deoxygenated hemoglobin shown by curve 44b and also the absorption spectra of oxygenated hemoglobin shown by curve 44a, i.e. blood, strongly absorb light in the red portion of the visible spectrum, especially for wavelengths shorter than 650 nm. At longer wavelengths in the infrared portion of the spectrum, i.e. above 950 nm, EMR is absorbed by water, i.e. by H2O, as shown by the absorption spectra of curve 42 and to a lesser degree by the absorption of lipids and fats shown by curve 43. In between 650 nm to 950 nm, human tissue is essentially transparent as illustrated by transparent optical window 45.
Aside from absorption by fats and lipids shown by curve 43, EMR comprising photons 23 of wavelengths λ within in transparent optical window 45, are directly absorbed by cytochrome-c oxidase as shown by the absorption spectra of curves 41a and 41b. Specifically, the 41b portion of the absorption spectra of cytochrome-c oxidase 24 is absorbed by infrared red unimpeded by water or blood. A secondary absorption tail for cytochrome-c oxidase shown by curve 42a illuminated by light in the red portion of the visible spectrum is partially blocked by the absorption properties of deoxygenated hemoglobin shown by curve 44b, limiting any photobiological response for deep tissue but still activated in epithelial tissue and cells. In this regard, phototherapy for skin and internal organs and tissue requires different treatments and light wavelengths, red for skin and infrared for internal tissue and organs.
Importance of Photonic Delivery System
In any case, to achieve maximum energy coupling into tissue during phototherapy, it is important to devise a consistent delivery system for illuminating tissue with photons consistently and uniformly. While early attempts used filtered lamps, lamps are extremely hot and uncomfortable for patients, potentially can burn patients and doctors, and are extremely difficult in maintaining uniform illumination during a treatment of extended duration. Lamps also suffer short lifetimes, and if constructed using rarified gasses, can also be expensive to replace regularly. Because of the filters, the lamps must be run very hot to achieve the required photon flux to achieve an efficient therapy in reasonable treatment durations. Unfiltered lamps, like the sun, actually deliver too broad a spectrum and limit the efficacy of the photons by simultaneously stimulating both beneficial and unwanted chemical reactions, some involving harmful rays, especially in the ultraviolet portion of the electromagnetic spectrum.
As an alternative, lasers were later used to perform phototherapy. Like lamps, lasers risk burning a patient, not through heat, by exposing tissue to intense concentrated optical power. To prevent that problem, special care must be taken that laser light is limited in its power output and that unduly high current producing dangerous light levels cannot accidentally occur. A second problem derives from a laser's small “spot size”, the illuminated area. Because a laser illuminates a small focused area it is difficult to treat large organs, muscles, or tissue and it is much easier for an overpower condition to arise. Another consideration of laser light is its “coherence” the property of light preventing it from spreading out, making it more difficult to cover large areas during treatment. Studies also reveal there is no inherent extra benefit from phototherapy using coherent light. For one thing, life evolved on scattered, not coherent light. Secondly, the first two layers of epithelial tissue already destroys any optical coherence, so the presence of coherence is really relegated to light delivery but not to its absorption.
Moreover, the optical spectrum of a laser is too narrow to fully excite all the beneficial chemical and molecular transitions needed to achieve high efficacy phototherapy. The limited spectra of a laser, typically a range of ±3 nm around the laser's center wavelength value, make it difficult to properly excite all the beneficial chemical reactions needed in phototherapy. For example, referring again to FIG. 3, clearly the chemical reactions involved in making the CCO absorption spectra 41b is clearly different than the reactions giving rise to absorption tail 41a. 
So just as sunlight has an excessively broad spectrum, photobiologically exciting many competing chemical reactions with many EMR wavelengths, some even harmful, laser light is too narrow and does not stimulate enough chemical reactions to reach full efficacy in phototherapeutic treatment. This subject is discussed in detail a related application entitled “Phototherapy System and Process Including Dynamic LED Driver with Programmable Waveform”, by Williams et. al. (U.S. patent application Ser. No. 14/073,371), incorporated herein by reference.
To deliver phototherapy by exciting the entire range of transparent optical window 45, i.e. the full 300 nm width, then even if four different wavelength light sources were employed to span the range, each light source would require a bandwidth almost 80 nm wide, more than an order of magnitude wider than that of a laser light source. This range is simply too wide for lasers to cover.
In contrast, today's commercially available light-emitting diodes (LEDs) are capable of emitting a wide range of light spectra from the deep infrared through the ultraviolet portion of the electromagnetic spectrum. To be effective therapeutically, however, the LEDs must be stably positioned atop the area to be treated. In FIG. 4A, for example, an LED wand or hairbrush 60 comprising a stiff array of LEDs suffers numerous issues, severely diminishing its utility and relegating its use to that of a toy. Its first issue is a matter of “fluence”, the total quantity of photons delivered by a phototherapy system during a treatment. Phototherapy treatments run between 20 minutes to over an hour and may involve several treatments in sequence. Since it takes time for cells to begin to react to biophotonic stimulation, applying a treatment for only a few minutes accomplishes nothing. But practically speaking, it is uncomfortable or nearly impossible to hold a handheld wand in one position for an hour or more.
The importance of maintaining the LED array in a constant position above tissue being treated is highlighted in the graphics of FIG. 4A, depicting an LED wand 60 being held at various distances above a treated array comprising epithelial layer 61 and subdermal tissue 62. In the leftmost case, where the LED wand 60 is held high above the treatment area, the light expands to cover a large area but only penetrates into the skin at a shallow depth 63, barely reaching subdermal tissue 62 where healing occurs. In the center case, LED wand 60 is held at an intermediate distance whereby the light spreads out less, covering a smaller area but penetrating into the tissue to a greater depth 64. In the rightmost case, LED wand 60 is held against epithelial layer 61 and penetrates deeply into subdermal tissue 62 to a greater depth 65 but with a much smaller area than that of the leftmost case shown. By moving the wand, an unavoidable condition in any real treatment, any and all of the cases shown may occur. Each time the epidermal tissue being treated changes by moving the placement of LED wand 60 the treated area and depth changes, essentially restarting the treatment.
The arrangement shown in FIG. 4B, which includes a stiff LED panel 66 that is strapped onto a patient is better in the sense that the LEDs are held firmly in place, but it still suffers from variable penetration depth because most human or animal appendages are treatment areas are not flat, but are curved. A stiff LED panel 66 cannot bend to adapt to the curves of a patient's body. The effect is that the light's penetration depth 67 in the center of the area being treated is much greater than the penetration depth 68 located under the edge of the panel 66 because it does not curve of flex to it the body.
FIG. 4C illustrates that the best solution to the light delivery problem is to employ a flexible LED pad, one that curves to a patient's body. As shown, flexible LED pad 70 may be bent to fit a body appendage.
The resulting benefit, shown in FIG. 4C illustrates that the resulting light penetration depth 76 into subdermal tissue 62 from the LEDs 72 comprised within flexible pad 70 is perfectly uniform along the lateral extent of the tissue being treated. Unlike the previous examples, where the light source as a stiff LED wand or inflexible LED panel are held above the tissue being treated, in this example the flexible LED pad 70 comes in contact with the patient's skin, i.e. epithelial 61. To prevent inadvertent spread of virulent agents through contact to LED pad 70, a disposable aseptic barrier 71, typically a clear plastic layer is inserted between light pad 70 and the patient.
To enable it to bend into various shapes, light pad 70 comprises a flexible polymeric material. Likewise, printed circuit board 71, to which LEDs 72 and integrated circuit package 74 are attached, may also comprise a flex PCB (printed circuit board) material. In such cases however, if the flex PCB 73 bends and LEDs 72 or integrated circuit package 74 do not, stress will be placed on any leads 75 used to attach the electronic component to flex PCB 73. Repeated stress can lead to stress fractures, poor reliability, and even open circuits.
Another consideration is manufacturing of the LED pads. If the flexible polymeric material is porous, chemically or biologically reactive, it can harbor viruses or bacteria in its surface cavities, infecting subsequent users, or retain harmful fluids, acids or toxins on its surface potentially harming the next patient to employ the LED pad. LED pads are often used in non-aseptic environments and may be applied onto infected or broken skin, e.g. over a cut or an acne pimple. If the polymeric pad is porous or is not inert and hypoallergenic, its repeated use may result in adverse reactions or cross-contamination among patients. The pad's polymeric material must also be compatible with regular alcohol or disinfectant cleanings needed to insure an aseptic contagion-free surface without degrading the polymer or impacting the LED pad's electrical function. Ideally it should also be compatible with disinfection in a UV or ozone disinfection chamber.
A complete phototherapy system for controlled light delivery available today, shown in the pictograph of FIG. 5, comprises an electronic driver 90 connected to one or more sets of flexible LED pads 91a-91e through cables 91a and 91b and connected to one other through short electrical connectors 93a-93d. 
Specifically, one electrical output of electronic driver 90 is connected to a center flexible LED pad 91a by an electrical cable 92a which is in to connected to associated side flexible LED pads 91b and 91c through electrical connectors 93a and 93b respectively. A second set of LEDs pads connected to a second electrical output of electronic driver 90 is connected to center flexible LED pad 91c by electrical cable 92b which is in turn connected to associated side flexible LED pads 91d and 91e through electrical connectors 93c and 93d respectively located on the edges perpendicular to the edge where electrical cables 92a and 92b attach.
FIG. 6 illustrates a schematic representation of the light delivery system comprising a set of three flexible LED pads with center flexible LED pad 105a and side flexible LED pads 105b and 105c. The center flexible LED pad 105a is identified by its integrated electrical cable 100 used to connect the LED pad to the electronic driver, including a plug 101 and a hardwired pad-to-cable connection 102. Center flexible LED pad 105a in turn connects to side flexible LED pads 105b and 105c (collectively as flexible LED pads 105) through short electrical connectors 103a and 103b, plugging into corresponding sockets 104, with two such sockets located on the edges of every flexible LED pads. On the center pad 105a these sockets 104 are located on the pad's edges perpendicular to the edge where electrical cable 102 attaches.
In this example, sockets 104 are located at the edge facing one another and interconnected electrically by straight electrical connector 103a and 103b. In other implementations the connectors face one another and are located in the center edge of the pads, as shown in FIG. 5. In a similar manner, the connectors face one another and are interconnected by straight electrical connectors 93a and 93b. Because the sockets face one another the straight electrical connectors must be made short in order to afford the opportunity to position the flexible LED pads close to one another. In therapeutic treatments, the flexible LED pads are held tightly in place by a Velcro belt 107 laid across the back of the pads oriented parallel to electrical connectors 103a and 103b and perpendicular to hardwired center pad-to-cable connection 102. Optional Velcro straps 108 may be glued to the flexible LED pads 105, except in practice it is easy to dislocate, literally rip, the Velcro straps 108 away from the flexible LED pads 105, in part because of the biologically inert material needed in their manufacture. If the lengths of straight electrical connectors 103a and 103b are made too long, or Velcro strap 107 is pulled too tightly, undue stress on the electrical connectors may result, resulting in wires torn from the connector plug, broken wires, or broken plugs, generally resulting in an open circuit.
Reliability Issues with Flexible LED Pads
While the need for flexible LED pads forms the basis of delivering consistent phototherapy to patient's skin and organs for extended durations, the pad's very flexibility is a fundamental source of reliability problems with their practical implementation.
For example, as an LED pad is used repeatedly, including being twisted, bent, curved, laid upon, and otherwise shaped to fit the contours of a patient's body, the repeated bending of the LED pad tends to move the PCB (or PCPs) contained within the LED pad till eventually many of the LEDs do not line up with the holes in the pad. For example, as shown in pictograph 120a of FIG. 7, LED pad 105a includes an array of openings 106 aligned to the LEDs emitting photons. A close-up of area 121 shown in pictograph 120b illustrates that while some LEDs 122 are properly aligned to the openings in pad 105a, others are laterally displaced like misplaced LED 123 covering part or all of the LED and blocking any light from being administered to a patient being treated.
Another issue, shown in FIG. 8, is that repeatedly bending a flex PCB may result in cracking of solder connecting component leads to the PCB. For example, in pictograph 125a LED 122 mounted onto PCB 123 exhibits after repeated use an electrical connection problem at solder connection 124c, shown in expanded detail 125b, were an electrical open circuit occurred as a result of crack 126 separating the LED's electrical connection, a copper lead, from the PCB conductive trace, resulting in an electrical failure in the LED pad.
FIG. 9 illustrates another problem resulting from repeated bending and handling of the flexible LED pad. In this case the electrical cable connecting the center flexible LED pad to the electronic driver experienced a failure in its hardwired pad-to-cable connection 102 where without sufficient strain relief, pulling on the cable dislodged the connector from the wire terminator 132 and created an electrical open circuit between electrical cable 102 and the pins 131 connected to the PCB resulting in a non-functional LED pad.
Similar failures occurred in the pad-to-pad electrical connectors 103 as shown in FIG. 10, where after repeated use cable 103b pulled out of plug 135 at failure point 136 to cause an electrical open circuit. Such failures can occur if the lengths of straight electrical connectors 103a and 103b exemplified in FIG. 6 are made too long, or Velcro strap 107 is pulled too tightly, resulting in undue stress on the electrical connectors whereby the wires may be broken or torn from the connector plug, resulting in an open circuit.
In the prior art design, then, broken wires, solder joints and leads are problematic, especially because the flexible LED pads are routinely stretched, bent, compressed and adjusted during treatments. Even in the case of attempts to use multiple stiff PCBs 140a, 140b, and 140c connected by jumper wires 141a and 141b within a flexible LED pad as shown in FIG. 11, repeated bending of the flexible LED pad eventually results in illustrated failure 142, where the wire jumper suffers an open circuit to the PCB conductive trace, breaking, the wire at the point of the solder joint. This observation is comparable to that of automotive manufacturers who claim that every discrete wire connected to an external rear view mirror costs million of dollars in replacement costs from wire breakage. As a result, eliminating and minimizing those wires is today a best practice in the automotive industry.
Another issue affecting consistent performance of any network of flexible LED pads is one of voltage drop in the wires and connectors resulting from electrical resistance. Using voltage control, the current in a particular series string of LEDs depends on the power supply voltage +VLED and the total series resistance between the particular string Rseries. Because the total series resistance is sensitive to the resistance within the flexible LED pads, the brightness of the LED string may not be uniform, depending on PCB manufacturing and the interconnection of the flexible LED pads by the user.
For example, FIG. 12A represents a simplified schematic drawing of a voltage driven LED phototherapy system comprising a LED controller unit 90 driving a set of three flexible LED pads 105a, 105b and 105c. As shown, LED pad 105a, the one with cable 100 connecting the pad to LED controller 90 through connector 101, is electrically located in the center between the other two LED pads 105b and 105c and supplies power to both LED pads 105b and 105c. This electrical configuration, one with a center pad connected to a power supply feeding power directly to two side pads, is for clarity sake referred to herein as a “T” configuration for connecting the LED pads. Within LED controller unit 90 is a controlled voltage source 150 that supplies a voltage +VLED whenever it is on and 0 volts when it is off. The supply may be turned on continuously or pulsed during an actual phototherapy treatment.
Within each flexible LED pad is an array of LEDs connected in a combination of series strings which themselves are connected in parallel. For clarity, most of the LEDs have been intentionally been omitted in FIG. 12A and FIG. 12C, where only the center and edge LED strings are shown. For example, for the pad 105a, i.e. one connected directly to LED controller 90, only center LED string 156a and edge strings 155a and 157a are illustrated. Any number of additional LED strings may be included between the LED strings shown. A similar arrangement exists for flexible LED pads 105b and 105c. Each LED string, depicted as single LEDs 155a, 156a, and 157a actually comprise a series circuit comprising a number of LEDs, from 1 to 40, and a bias resistor despite the fact that only a single LED is shown.
For clarification of terminology, note the term “center” pad is sometimes used to identify LED pad 105a as a pad with connected cable 100 and to distinguish it from other LED pads lacking connected cables regardless of the pads are topologically interconnected. The presumption that any LED pad with a connected cable is by definition the “center” pad as shown by pad 105a in the T-shaped electrical topology shown in FIG. 12A, is in recognition that electrically configuring the pads in an L-shaped circuit topology as shown in FIG. 12C with pad 105a on the end, is electrically inferior because the current must flow through a longer path with greater series resistance.
An example of the equivalent circuit of LED 156a is shown in FIG. 12B comprising series-connected LEDs 158a, a series of in LEDs 1 through m as shown, and bias resistor 159a. The bias resistor 159a may range from 1 ohm to several hundred ohms, but it cannot be so high in value as to prevent the required current from flowing. The current ILED through each string can be calculated with the following equation:ILED=(Vbias−m·Vf)/Rbias 
wherein Vbias is the voltage applied across the serial combination of LED string 158a and bias resistor 159a, m is the number of series-connected LEDs in the LED string 158a, Vf is the average forward voltage drop of each of the LEDs 1 through m in LED string 158a during conduction, and Rbias is the resistance of bias resistor 159a. For example, if Vbias=30V, m=20, and Vf=1.4V, and Rbias=67Ω then (Vbias−m·Vf)=2V and ILED=30 mA.
Returning to FIG. 12A, each flexible LED pad contains parasitic resistance associated with the PCB conductive traces depicted as resistors 151a, 152a, 153a an 154a in flexible LED pad 105a and similarly in the other LED pads. Ideally these parasitic resistances are zero and the only resistance present in the LED pad is the discrete Rbias resistor used to set the LED currents. In such a case no voltage drop occurs across the conductive traces and the entire supply voltage is biased across each and every LED string, i.e. where +VLED=Vbias. In prior art flexible LED pads, however, the PCB conductive traces have resistance and exhibit a voltage drop, red the Vbias voltage on each LED string and affecting the LED brightness. The problem of parasitic resistance is further exaggerated in the case of flexible PCBs, which naturally employ thinner conductive traces in order to maintain flexibility.
If all the voltage drops resulting, from parasitic resistance were uniform, the LEDs would be uniformly less bright, and the problem could be adjusted simply by changing the value of the supply voltage +VLED or the bias resistors Rbias to correct for the effect of the parasitic resistance. The problem however, is that the effect of the parasitic resistance is not uniform and in fact, depends on the PCB layout and even on the way the LED pads are connected. For example, in the T configuration shown in FIG. 12A, the center pad 105a supplies power to the side pads 105b and 105c in the shortest possible path, meaning power entering flexible LED pad 105a through cable 100 is delivered to connector 103a and flexible LED pad 105b through only two resistors 152a and 154a, and does not flow through flexible LED pad 105c. Similarly, power entering flexible LED pad 105a through cable 100 is also delivered to connector 103b and flexible LED pad 105c through only two resistors 151a and 153a, and does not flow through flexible LED pad 105b. 
Even though in the T configuration power does not flow through multiple pads, resistance within a pad results in a gradation of voltage across the LED array within a pad. For example, power is delivered to LED string 155b in flexible LED pad 105b through only two parasitic resistors 152a and 154a, but power to LED string 157b is conducted through six parasitic resistors, namely 152a, 151b, 152b, 154b, 153b, and 154a, a factor of three higher parasitic resistance. The problem of distributed parasitic resistance is manageable within a single pad because the current within a given pad is limited to a maximum of n·ILED, where “n” is the number of LED strings in a given LED pad and ILED is the current flowing through each string of LEDs. For example, in the T configuration shown in FIG. 12A, the total current flowing through connectors 103a and into flexible LED pad 105b assuming n=10 and ILED=30 mA is only 300 mA in total.
If however, the flexible LED pads are configured in an “L” shaped configuration shown in FIG. 12C where the power supply connected flexible LED pad 105a is connected at the end of a set of three interconnected LED pads, the parasitic resistance problem is significantly worse. Consider the series parasitic resistance of the circuit driving the farthest LED string 155b in the circuit, comprising 10 parasitic resistors 151a, 152c, 151c, 152b, 151b, 153b, 154b, 153c, 154c, and 153a. The L configuration results in 67% more parasitic resistance, i.e. 10/6 times, than the same LED pads connected in at T configuration. The user may then experience a diminished brightness in flexible LED pad 105b, the last LED pad in the chain. Moreover, the PCB traces in flexible pad 105c connected to connector 103b must carry all the current for both flexible LED pads 105c and 105b, i.e. a total of 600 mA. In prior art flexible LED pads, the performance and even LED pad reliability suffer whenever users connect the LED pads in the L configuration. While user instructions advise the LED pads should not be connected in the L configuration, for applying treatment from the base of the neck and down the spine it is inconvenient to use the T configuration unless the patient removes their shirt or blouse.
Another consideration in flexible pad design, including cabling, is that of electrical noise and electromagnetic compatibility, or EMC. Since the total current being pulsed on and off in a set of three pads can exceed 900 mA and may be modulated at 20 kHz frequencies or greater, shielding and noise management is an important consideration, especially in order to pass FCC class-B certification needed for medical devices. Inadequate shielding can result is several issues, including false turn on of LEDs. For example, without proper shielding, driving a LED pad comprising both red and infrared LEDs can result in the red LEDs being slightly illuminated when only the infrared LEDs are being pulsed, a consequence of capacitive coupling between control lines used to turn the separate LED strings on and off. For example, in the pictograph of FIG. 13, a flexible LED pad 105a comprises both red and infrared LEDs. A special electronic camera 170 is able to “see” both infrared and red light and to display the camera images of both visible and infrared light on an LCD display with visible light. Even though only the infrared LEDs should be illuminated in the example shown, if flexible LED pad 105a is operated by pulsing the infrared LEDs on and off while maintaining the red LEDs in an off condition, both the infrared. LEDs and the red LEDs simultaneously conduct and both generate light. The magnitude of the problem increases in proportion to the modulating frequency of the infrared LEDs, indicating the noise coupling is capacitive (because the impedance of a capacitor and hence the noise coupling decreases with increasing frequency). The greater the magnitude of capacitive coupling, the more pronounced the noise coupling effect, meaning longer cables exhibit greater noise sensitivity than shorter cables. Short cables, however, limit physicians in their ability to comfortably perform treatments on customers in crowded clinic rooms. In the gray-scale drawing of FIG. 13, the illuminated LEDs on the pad 105a correspond to the bright images 172 on the screen of camera 170, the only LEDs that should be illuminated. But as illustrated, the dim images 171 on the screen of camera 170 reveal off state LEDs, LEDs that should not emit light or be present in the LCD image, are in fact emitting light. Light emission from LEDs biased into and off condition represents a malfunction.
So in the present generation of flexible LED pads, the use of flex PCBs results in broken solder connections between component leads and the flex PCBs, while the used of stiff PCBs results in broken wire and broken solder joints where the jumper wires connect to the PCB conductive traces. Either way, the result is a broken conductive path and intermittent operation or permanent disabling of the LED pad's operation. For these and many other reasons, the majority of the product offerings in phototherapy today utilize hard, stiff and inflexible pads—pads that do not contour to a patient's body and appendages, and therefore do not uniformly administer phototherapeutic treatment in a consistent or beneficial manner, sacrificing treatment efficacy for product reliability. Flexible LED pads sold to consumers, break and malfunction easily, and are not designed to work reliably after repeated use, especially in their professional application as used by doctors, therapists and clinics for humans or for animals.
What is needed is a new design for, and a means to manufacture flexible LED pads for phototherapy that do not suffer the aforementioned reliability and performance failures caused by improperly positioned or dislocated LEDs; broken connectors, wires, and solder joints; parasitic resistance; and noise.